Conventionally, a group of electrical wires is inserted into and held in a grommet formed by a rubber elastic body made of rubber, an elastomer, or the like, and then the grommet is fitted into a through-hole formed in a vehicle body panel that partitions the engine room and the compartment of an automobile, thus routing the group of electrical wires while also ensuring waterproofing between the engine room and the vehicle compartment (e.g., see Patent Document 1 JP2012-100396A).
A grommet 101 shown in FIG. 14 has the same configuration as that described in Patent Document 1. A wire harness 108 is constituted by a grommet 101, which is indicated by solid lines and is closely fitted into a circular through-hole H1 formed in a vehicle body panel P that is a partition wall between an engine room X and a compartment Y, and a group of electrical wires 102, which is indicated by dashed double-dotted lines and is inserted through and fixed to the grommet 101. The grommet 101 includes: a first cylindrical portion 103 that has a cylindrical shape; a second cylindrical portion 104 that has a cylindrical shape and coaxially surrounds an axially intermediate portion of the first cylindrical portion 103; a seat portion 105 that coaxially surrounds the first cylindrical portion 103 and the second cylindrical portion 104 and is to be mounted to the through-hole H1 of the vehicle body panel P; a first wall portion 106 that extends in the circumferential direction, is integrally continuous with the outer peripheral surface of the axially intermediate portion of the first cylindrical portion 103 and the inner peripheral surface of an axially intermediate portion of the seat portion 105, and has a mountain-shaped bent portion 106a in which the cross-sectional shape along the axis is bent in a mountain shape toward the compartment Y side; and a flare-shaped second wall portion 107 having a large-diameter end on the compartment Y side that is integrally continuous with a portion of the first wall portion 106 that is radially outward of the mountain-shaped bent portion 106a, and having a small-diameter end on the engine room X side that is integrally continuous with an end portion on the compartment Y side of the second cylindrical portion 104.
The edge portion (on the inner circumferential side) of the opening of the through-hole H1 of the vehicle body panel P is formed as a short conical cylinder-shaped flange that is bent toward the engine room X side. The seat portion 105 has an annular groove portion 105a that has a conical cylindrical surface that corresponds to the flange of the through-hole H1, and the flange of the through-hole H1 of the vehicle body panel P is fitted into the outer peripheral portion.
The portion of the group of electrical wires 102 that projects from the first cylindrical portion 103 toward the engine room X side, and the end portions, on the engine room X side, of the first cylindrical portion 103 and the second cylindrical portion 104 are integrally fixed to each other by a tape-wrap fixing portion T in which adhesive tape is wrapped.
With the wire harness 108, when the grommet 101 is arranged on the compartment Y side of the vehicle body panel such that the second cylindrical portion 104 faces the engine room X side, and then the group of electrical wires 102 is inserted into the through-hole H1 of the vehicle body panel P and pulled to the engine room X side, the first cylindrical portion 103 and the second cylindrical portion 104 pass through the through-hole H1, and the outer peripheral portion of the seat portion 105 is caught on the inner peripheral edge portion of the through-hole H1 of the panel P.
With the wire harness 108, when the group of electrical wires 102 is pulled more strongly to the engine room X side, the seat portion 105 deforms elastically, the flange of the through-hole H1 of the panel P becomes fitted into the annular groove portion 105a of the seat portion 105, and the grommet 101 becomes fixed to the vehicle body panel P.